Andrew's git / gitweb.git /
a9bc6240202f7c11cce396f102984e0ee480a244
   1#ifndef HASH_H
   2#define HASH_H
   3
   4#include "git-compat-util.h"
   5
   6#if defined(SHA1_PPC)
   7#include "ppc/sha1.h"
   8#elif defined(SHA1_APPLE)
   9#include <CommonCrypto/CommonDigest.h>
  10#elif defined(SHA1_OPENSSL)
  11#include <openssl/sha.h>
  12#elif defined(SHA1_DC)
  13#include "sha1dc_git.h"
  14#else /* SHA1_BLK */
  15#include "block-sha1/sha1.h"
  16#endif
  17
  18#include "sha256/block/sha256.h"
  19
  20#ifndef platform_SHA_CTX
  21/*
  22 * platform's underlying implementation of SHA-1; could be OpenSSL,
  23 * blk_SHA, Apple CommonCrypto, etc...  Note that the relevant
  24 * SHA-1 header may have already defined platform_SHA_CTX for our
  25 * own implementations like block-sha1 and ppc-sha1, so we list
  26 * the default for OpenSSL compatible SHA-1 implementations here.
  27 */
  28#define platform_SHA_CTX        SHA_CTX
  29#define platform_SHA1_Init      SHA1_Init
  30#define platform_SHA1_Update    SHA1_Update
  31#define platform_SHA1_Final     SHA1_Final
  32#endif
  33
  34#define git_SHA_CTX             platform_SHA_CTX
  35#define git_SHA1_Init           platform_SHA1_Init
  36#define git_SHA1_Update         platform_SHA1_Update
  37#define git_SHA1_Final          platform_SHA1_Final
  38
  39#ifndef platform_SHA256_CTX
  40#define platform_SHA256_CTX     SHA256_CTX
  41#define platform_SHA256_Init    SHA256_Init
  42#define platform_SHA256_Update  SHA256_Update
  43#define platform_SHA256_Final   SHA256_Final
  44#endif
  45
  46#define git_SHA256_CTX          platform_SHA256_CTX
  47#define git_SHA256_Init         platform_SHA256_Init
  48#define git_SHA256_Update       platform_SHA256_Update
  49#define git_SHA256_Final        platform_SHA256_Final
  50
  51#ifdef SHA1_MAX_BLOCK_SIZE
  52#include "compat/sha1-chunked.h"
  53#undef git_SHA1_Update
  54#define git_SHA1_Update         git_SHA1_Update_Chunked
  55#endif
  56
  57/*
  58 * Note that these constants are suitable for indexing the hash_algos array and
  59 * comparing against each other, but are otherwise arbitrary, so they should not
  60 * be exposed to the user or serialized to disk.  To know whether a
  61 * git_hash_algo struct points to some usable hash function, test the format_id
  62 * field for being non-zero.  Use the name field for user-visible situations and
  63 * the format_id field for fixed-length fields on disk.
  64 */
  65/* An unknown hash function. */
  66#define GIT_HASH_UNKNOWN 0
  67/* SHA-1 */
  68#define GIT_HASH_SHA1 1
  69/* SHA-256  */
  70#define GIT_HASH_SHA256 2
  71/* Number of algorithms supported (including unknown). */
  72#define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1)
  73
  74/* A suitably aligned type for stack allocations of hash contexts. */
  75union git_hash_ctx {
  76        git_SHA_CTX sha1;
  77        git_SHA256_CTX sha256;
  78};
  79typedef union git_hash_ctx git_hash_ctx;
  80
  81typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);
  82typedef void (*git_hash_update_fn)(git_hash_ctx *ctx, const void *in, size_t len);
  83typedef void (*git_hash_final_fn)(unsigned char *hash, git_hash_ctx *ctx);
  84
  85struct git_hash_algo {
  86        /*
  87         * The name of the algorithm, as appears in the config file and in
  88         * messages.
  89         */
  90        const char *name;
  91
  92        /* A four-byte version identifier, used in pack indices. */
  93        uint32_t format_id;
  94
  95        /* The length of the hash in binary. */
  96        size_t rawsz;
  97
  98        /* The length of the hash in hex characters. */
  99        size_t hexsz;
 100
 101        /* The block size of the hash. */
 102        size_t blksz;
 103
 104        /* The hash initialization function. */
 105        git_hash_init_fn init_fn;
 106
 107        /* The hash update function. */
 108        git_hash_update_fn update_fn;
 109
 110        /* The hash finalization function. */
 111        git_hash_final_fn final_fn;
 112
 113        /* The OID of the empty tree. */
 114        const struct object_id *empty_tree;
 115
 116        /* The OID of the empty blob. */
 117        const struct object_id *empty_blob;
 118};
 119extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];
 120
 121/*
 122 * Return a GIT_HASH_* constant based on the name.  Returns GIT_HASH_UNKNOWN if
 123 * the name doesn't match a known algorithm.
 124 */
 125int hash_algo_by_name(const char *name);
 126/* Identical, except based on the format ID. */
 127int hash_algo_by_id(uint32_t format_id);
 128/* Identical, except for a pointer to struct git_hash_algo. */
 129static inline int hash_algo_by_ptr(const struct git_hash_algo *p)
 130{
 131        return p - hash_algos;
 132}
 133
 134#endif